Method for manufacturing of composite door panel using injection molding technology

ABSTRACT

A method to produce one-piece high-density panel skin (outer part of the door panel) using a specially designed 25 ton mold operated on a 3000 ton injunction molding machine using performance engineering grade poly phenyl impact copolymer as raw material. 
     The two injection molded panels are joined using a custom extruded aluminum frame, with a provision for an improved lock along the whole length and hinges, fitted with specially designed hot plate welded skin holder, subsequently filled with polyurethane for rigidity, strength and high insulation valve. For additional reinforcement for the entry door, 18 gauge CRC steel barrier is embedded in rigid polyurethane core. 
     A door panel produced by the above methods.

This application claims priority of Pakistani patent application Serial No. 501/2006, filed May 20, 2006, the disclosure of which is incorporated herein in its entirety by reference for all purposes.

FIELD OF THE INVENTION

The present invention generally relates doors and specifically to a composite door panel, which would be less costly for houses and office construction, would guarantee against corrosion.

BACK-GROUND OF THE INVENTION

The house building industries are developing very fast but no work has been done to change the material of door and windows in a house or office. The front entry doors and interior doors for residential houses and offices have historically been made of wood or steel, recently fiber glass and vinyl doors are available. The wooden doors deteriorate with time and need a great care for its maintenance. Steel doors dent very easily and are prone to corrosion. Fiberglass doors are comparatively expensive and vinyl doors generally lack the aesthetic quality. Under the circumstances, it is desirable that some new article should be introduced, which should be durable and friendly to pocket.

Therefore, the present invention has been developed in an effort to solve the above described problems in the prior art. It is a first objective of the present invention to introduce a new product, while overcoming the limitations of available products, alternative materials and processes to manufacture door panels.

It is a second objective of the present invention to provide a door, which would be less costly for home construction, would guarantee against corrosion and other environmental effects and withstand harshest weather conditions and also to qualify for all the test standard requirements of International Building Standards.

SUMMARY OF THE INVENTION

An embodiment of the present invention is an improved method for manufacturing door panels comprising using injection moldings technology to produce one-piece high-density panel comprising at least two panel skins. In another embodiment the method further comprises using a specially designed 25 ton mold operated on a 3000 ton injunction molding machine and polypropylene as raw material.

In another embodiment, the invention further comprises joining of the panel skins using an improved custom extruded aluminum frame with a provision for non-returnable lock and hinges, fitted with specially designed hot plate welded skin holder, subsequently filled with polyurethane.

In yet another embodiment, the method further comprises an additional reinforcement of 18 gauges cold rolled coil (CRC) steel barrier is embedded in the rigid polyurethane.

In another embodiment of the invention, the polypropylene used in the method is a performance engineering grade polypropylene impact copolymer.

In another embodiment, the surface of the skin of the door panel is mechanically roughened to create strong adhesion between the skin and adhesive.

In another embodiment of the invention, the panel skins are joined using a custom extruded aluminum frame, specially designed to hold the skin from all the side, with the provision of non-returnable lock along the full length of aluminum profile to ensure perfect locking system. The panel skins are further supported by specially designed hot plate welded skin holder.

In another embodiment of the invention, the method comprises filling the remaining space of the inner portion of the skin with polyurethane for rigidity, strength and high insulation value with the help of a specially designed press machine, which hold the skin during filling.

In a further embodiment, the invention is an improved method for manufacturing of door panels using injection molding technology to produce one-piece high-density panel skins, wherein the method comprises joining of the two injection molded panel skins, using a specially designed 25 ton mold operated on a 3000 ton injection molding machine, performance engineering grade mechanically roughened polypropylene impact copolymer as raw material, and an improved custom extruded aluminum frame with provision of non-returnable lock and hinges, fitted with specially designed hot plate welded skin holder, subsequently filled with polyurethane for rigidity, strength and high insulation value, a reinforcement of 18 gauges cold rolled coil (CRC) steel barrier embedded in rigid polyurethane core, wherein the surface of the skin of the door panel is mechanically roughened to create strong adhesion between the skin and adhesive.

Another embodiment of the invention is a door made by any of the above methods.

DESCRIPTION OF DRAWINGS

FIG. I shows the cross-section of composite door panel.

FIG. II shows main outlook of the composite door panel.

FIG. III shows the position of 18 gauge CRC sheet, exclusive requirement of “entry door”.

FIG. IV shows the dimension of the skin holder and hot plate.

FIG. V shows the position of skin holder in the composite door panel.

In Figures the numeral 1 is the injection molded surface (skin of the door panel), 2 is slush molded rigid PV core, 3 is hot plate (Welded Skin holder), 4 is a layer of adhesive coating for skin and core, 5 is extruded aluminum frame, 6 is 18 gauge CRC sheet, 7 is the knob/lock of the door.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the invention is a new method for manufacturing of composite door panel, which is an improvement over the patent application Serial No. 961/2004, filed in Pakistan, which is hereby incorporated herein in its entirety by reference.

An embodiment of the invention is a door which is a great improvement over other products available in the market as its price is competitive, would not dent or corrode and would not absorb moisture, warp, and rot and has longer life and maintenance free performance over competitive products. Also the aesthetic appearance could match any home design.

An embodiment of the invention comprises of following:

-   -   i) innovative injection molded skin,     -   ii) specially designed Aluminum extruded frame, with a         non-returnable lock along the full length,     -   iii) specially designed hot plate skin holder,     -   iv) core of rigid polyurethane slush molding, and     -   v) 18 gauge cold rolled coil (CRC) steel barrier.

The injection molded surface (skin of the door) marked 1 is prepared by using injection molding technology, then the skin holder (3) are hot welded with hot melt joining of the two. Then the specially designed aluminum frame (5) is fixed with the help of an adhesive, with provision for lock and hinges and the 18 gauge CRC sheet (6) if required. The skin holder is fixed as shown in FIG. V. After fixing the skin holder (3), 18 gauge CRC sheet (6) and aluminum frame (5), the skins are then shifted to press machine, where polyurethane core is filled under constant pressure and the door of the invention is completed by applying the hinges and locks and then finished for painting.

An embodiment of the present invention is a method using the improved extruded aluminum frame, whereby a non returnable lock is added along the full length of aluminum profile to ensure perfect locking system and further the surface of poly phenyl plastic is mechanically roughened to create strong adhesion of adhesive and plastic as prior to this it was observed that during accidental hit on the edge of the door, there was no grip of plastic with aluminum, resulting in dislocation. Hence in order to improve the grip this invention has been made, as there is no adhesive is developed by now, which can grip poly phenyl plastic, therefore only possibility is to grip this plastic surface mechanically.

For further strength requirements of entry doors an additional reinforcement of 18-Gauge CRC steel sheet barrier is embedded in the rigid polyurethane core.

The doors of the present invention are manufactured using injection molding technology to produce one-piece high-density panel skins using a specially designed 25 Ton molded operated on a 3000 Ton injunction molding machine using performance engineering grade polyphenyl impact copolymer as raw material having the following typical properties:

Typical Properties Test Method Unit Value Melt flow rate (230° C., ASTM-D1238 g/10 min 32 2.16 kg) Density ASTM-D792 g/cm³ 0.898 Tensile strength at ASTM-D638 Kg/cm³ 250 yield Elongation at yield ASTM-D638 100 7 (Breakage) 100% Flexural modules ASTM-D 790 Kg/cm² 11600 Rockwell harness ASTM-D 785 R Scale 83 Heat deflection ASTM-D 648 ° C. 88 temperature Izod Impact Strength ASTM-256 Kg-cm/cm 6/46 Notched, 23° C./un- notched-18° Drop weight Impact TPP ft/lb 18 Strength Texture up, 29° C. Mold linear Shrinkage ASTM D 955 100 1.1 (in inches)

The two injection molded skins are joined using a specially designed extruded aluminum frame, with provisions of locks and hinges, fitted with specially designed hot plate welded skin holders, subsequently filled with polyurethane for rigidity strength and high insulation value.

The skin holders as described in FTG TV are the main feature of the invention and their holding strength is calculated as under:

Data

i. Holding strength of rigid polyurethane (PU)=2.5 kg/in²

ii. Total targeted force to hold skin=100 kg/side

iii. Force generating medium=25% Chemical Bond & 75% Mechanical Bond

iv. Thickness of PU=½ inch

Calculation of Force Generated by Skin Holder Overall force to be generated by Skin Holder=75 Kg/side Projected number of skin holder=10. Force required to be generated/holder=7.5/10=7.5 Kg Surface area required to hold the shear force=7.5/2.5=2.95 in² Shear area=II×D×Th=3.142×2×0.5

2.95=3.142×D×0.5

-   -   D=1.87 inches.

Including safety factor of 10%=1.87/0.1

-   -   D=2 inches

For binding the polyurethane in between the two skin adhesive coating is done with 3M Fast bond 30 or 3M Fast bond 40 adhesive, which has shown the best result as the base of the said adhesive is polychloropropane. The skin holders are joined with the skin with hot melt joining (hot welding). 

1. An improved method for manufacturing of door panels comprising using injection moldings technology to produce one-piece high-density panel comprising at least two panel skins.
 2. The method of claim 1, wherein the method further comprises using a specially designed 25 ton mold operated on a 3000 ton injunction molding machine and polypropylene as raw material.
 3. The method of claim 2, wherein the further comprises joining of the panel skins using an improved custom extruded aluminum frame with a provision for non-returnable lock and hinges, fitted with specially designed hot plate welded skin holder, subsequently filled with polyurethane.
 4. A method as claimed in claim 3, wherein an additional reinforcement of 18 gauges cold rolled coil (CRC) steel barrier is embedded in the rigid polyurethane.
 5. A method as claimed in claim 2, wherein the polypropylene is performance engineering grade polypropylene impact copolymer.
 6. A method as claimed in claim 1, wherein the surface of the skin of the door panel is mechanically roughened to create strong adhesion between the skin and adhesive.
 7. A method as claimed in claim 1, wherein the panel skins are joined using a custom extruded aluminum frame, specially designed to hold the skin from all the side, with the provision of non-returnable lock along the full length of aluminum profile to ensure perfect locking system.
 8. A method as claimed in claim 1, wherein the panel skins are further supported by specially designed hot plate welded skin holder.
 9. A method as claimed in claim 1, wherein the remaining space of the inner portion of the skin is filled with polyurethane for rigidity, strength and high insulation value with the help of a specially designed press machine, which hold the skin during filling.
 10. The door panel as prepared by the method of claim
 1. 11. The door panel as prepared by the method of claim
 2. 12. The door panel as prepared by the method of claim
 3. 13. The door panel as prepared by the method of claim
 4. 14. The door panel as prepared by the method of claim
 5. 15. The door panel as prepared by the method of claim
 6. 16. The door panel as prepared by the method of claim
 7. 17. The door panel as prepared by the method of claim
 8. 18. The door panel as prepared by the method of claim
 9. 19. An improved method for manufacturing of door panels using injection molding technology to produce one-piece high-density panel skins, wherein the method comprises joining of the two injection molded panel skins, using a specially designed 25 ton mold operated on a 3000 ton injection molding machine, performance engineering grade mechanically roughened polypropylene impact copolymer as raw material, and an improved custom extruded aluminum frame with provision of non-returnable lock and hinges, fitted with specially designed hot plate welded skin holder, subsequently filled with polyurethane for rigidity, strength and high insulation value, a reinforcement of 18 gauges cold rolled coil (CRC) steel barrier embedded in rigid polyurethane core, wherein the surface of the skin of the door panel is mechanically roughened to create strong adhesion between the skin and adhesive.
 20. The door panel as prepared by the method of claim
 19. 